I.e., 'bachelor of applied science' and 'bachelor of engineering' have a specific and strictly defined and even legally controlled meaning. I just don't see how the word 'shodan' has any kind of definable meaning comparable to that. It's just a word, and it means whatever one teacher or another is used to it meaning, or decides it would be convenient or useful for it to mean.

The kyu and dan ranks in aikido are like the coloured belts we use in kids' class - they're just a pedagogical tool, with no defined meaning or consequences.